Remove some unneeded NULL checks

Found by Coverity; also see commit 85fb2af3.

audio/filter/af_export.c

@@ -78,7 +78,6 @@ static int control(struct af_instance* af, int cmd, void* arg)
     int mapsize;
 
     // Free previous buffers
-    if (s->buf)
     free(s->buf[0]);
 
     // unmap previous area
@@ -94,8 +93,10 @@ static int control(struct af_instance* af, int cmd, void* arg)
 
     // Allocate new buffers (as one continuous block)
     s->buf[0] = calloc(s->sz*af->data->nch, af->data->bps);
-    if(NULL == s->buf[0])
+    if(NULL == s->buf[0]) {
       MP_FATAL(af, "Out of memory\n");
+      return AF_ERROR;
+    }
     for(i = 1; i < af->data->nch; i++)
       s->buf[i] = (uint8_t *)s->buf[0] + i*s->sz*af->data->bps;
 
@@ -147,7 +148,7 @@ static int control(struct af_instance* af, int cmd, void* arg)
 static void uninit( struct af_instance* af )
 {
     af_export_t* s = af->priv;
-    if (s->buf)
+
     free(s->buf[0]);
 
     // Free mmaped area

input/keycodes.c

@@ -305,7 +305,7 @@ int mp_input_get_keys_from_string(char *name, int max_num_keys,
 
     ptr = name;
     n = 0;
-    for (end = strchr(ptr, '-'); ptr != NULL; end = strchr(ptr, '-')) {
+    for (end = strchr(ptr, '-'); ; end = strchr(ptr, '-')) {
         if (end && end[1] != '\0') {
             if (end[1] == '-')
                 end = &end[1];

options/m_option.c

@@ -2288,13 +2288,11 @@ bool m_obj_list_find(struct m_obj_desc *dst, const struct m_obj_list *l,
         if (bstr_equals0(name, dst->name))
             return true;
     }
-    if (l->aliases) {
     for (int i = 0; l->aliases[i][0]; i++) {
         const char *aname = l->aliases[i][0];
         const char *alias = l->aliases[i][1];
         const char *opts  = l->aliases[i][2];
-            if (bstr_equals0(name, aname) &&
-                m_obj_list_find(dst, l, bstr0(alias)))
+        if (bstr_equals0(name, aname) && m_obj_list_find(dst, l, bstr0(alias)))
         {
             if (opts) {
                 dst->init_options = opts;
@@ -2306,7 +2304,6 @@ bool m_obj_list_find(struct m_obj_desc *dst, const struct m_obj_list *l,
             return true;
         }
     }
-    }
     return false;
 }
 

stream/rar.c

@@ -438,12 +438,11 @@ ssize_t RarRead(rar_file_t *file, void *data, size_t size)
         if (max <= 0)
             break;
 
-        int r = file->s ? stream_read(file->s, data, max) : -1;
+        int r = stream_read(file->s, data, max);
         if (r <= 0)
             break;
 
         total += r;
-        if( data )
         data = (char *)data + r;
         file->i_pos += r;
         if (file->i_pos >= chunk_end &&